This Saturday, NOAA is holding its final Hawaiian Islands Humpback Whale National Marine Sanctuary Ocean Count from 8 a.m. to 12:15 p.m. on Oahu, Kauai and the Big Island.

As many as 12,000 humpback whales — an endangered species — winter in Hawaiian waters each year. Humpback whale season in Hawaii generally runs from November through May, though the giant cetaceans may still be encountered in limited numbers during other months.

Volunteers help count whale sightings at NOAA's various sites from the shorelines of Oahu, Kauai and the Big Island.

Volunteers can still register for this Saturday's count on Oahu or the Big Island by visiting hawaiihumpbackwhale.noaa.gov. To volunteer on Kauai, call 808-246-2860.

All three islands saw record numbers of volunteers in January and February.

For the month of February, volunteers counted an average of five whales every 15 minutes from Oahu and Kauai, and an average of four every 15 minutes on the Big Island, similar to last year, according to a Star-Advertiser report.

Several other green goings-ons are also happening this Saturday, including an Adopt-A-Beach cleanup on the North Shore, Earth Hour (from 8:30 to 9:30 p.m.), and the Surfrider Foundation's "Rise Above Plastics" fundraiser party at the Waikiki Aquarium.